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| Treatment of Contaminated Sediments by Chemical Oxidation pp. 279-300 |
$100.00 |
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Authors: (Sabrina Saponaro, Alessandro Careghini, Kevin Gardner, Scott Greenwood, Politecnico di Milano, Dipartimento di Ingegneria Idraulica, Ambientale, Rilevamento, Infrastrutture Viarie – Sezione Ambientale, Piazza Leonardo da Vinci 32 – 20133 Milano (Italy), and others)
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Abstract:
A number of different approaches can be used when managing contaminated sediments depending on site-specific conditions, sediment characteristics, mix of contaminants in the sediment and local regulations. Ex situ management options can include landfill disposal or, more generally, the application of remediation treatments for beneficial reuse, which may improve the economics of management and/or be required to meet regulatory requirements.
Chemical oxidation involves the use of chemical additives to remediate sediments contaminated by organic compounds. Due to electron transfers between two (or more) compounds, pollutants are degraded into less toxic or biologically available chemical forms. Chemical oxidation also changes the pH and redox conditions of the treated system, which may also alter the mobility of the target and other compounds and elements.
Several different oxidizing agents are available that result in different effectiveness on different pollutants. The most commonly used oxidants are Fenton-like reagents (hydrogen peroxide catalyzed by bivalent iron ions), ozone, permanganate, and persulfate. Recent laboratory studies have also shown good results in peroxy-acid systems (an organic acid mixed with hydrogen peroxide) to degrade compounds such as Polycyclic Aromatic Hydrocarbons (PAHs).
Oxidation is a non-selective process. Therefore, the oxidizable material within the sediment (natural organic matter, detritus, etc.), which may be a significant percentage of the sediment mass, can consume the oxidizing agent. Moreover, many different reactions can occur (acid/base reactions, sorption/desorption, dissolution, hydrolysis, ion exchange, oxidation/reduction, precipitation, etc.). Pollutant removal efficiency strictly depends on the contamination (pollutants, concentrations) and the sediment being treated (physical-chemical properties and composition). Laboratory tests are always necessary to evaluate the feasibility of the treatment to select the best oxidizer and the proper treatment configuration.
This chapter reports on laboratory batch tests conducted on sediments from Porto Marghera (Italy) and New York/New Jersey Harbor (NY, USA). Porto Marghera sediments were treated with Fenton-like reagents to remove total petroleum hydrocarbons, PAHs, and polychlorinated biphenyls. Different oxidizers (Fenton-like reagents, persulfate, and peroxy-acid) were used for the New York City sediments polluted by PAHs. For the latter sediments, the leachability of metals in the treated sediments and filtration resistance were also assessed to understand potential unintended consequences of treatment on metal availability and sediment dewatering operations. |
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